I can't get Hammer to launch anymore... help?

I changed the environment variables thing like suggested in another thread, and I validated the game files, but I still can't get Hammer to launch. I'm using the .bat in the bin folder like I think I should be. It worked fine yesterday, but now it just won't launch anymore. I also kinda need it to work, since I'm making a TF2 map for a school project. Does anyone know what might be causing this, or how to fix it?

It turns out the .bat doesn't work anymore (for whatever reason). I just used the Hammer.exe in the bin folder and now it works fine.